Set on the Kansas plains in the early 1890s, the series follows the story of a young evangelist named Mercy Randolph as she discovers God's love through an unlikely friendship with a card-playing drifter named Jeremiah Eagleflight.

Mercy Randolph, at home in Sweetriver, Kansas, finds herself in the midst of danger moving as fast as a tornado. Meanwhile, Jeremiah must learn to deal with his new faith and his new love—while risking everything to save his nephew from enemies.